Analysis of Spatial Mechanisms for Quasi-Direct Drive Redundant Robots.

Abstract : A serial-parallel robotic manipulator can be viewed as a closed mechanism with multiple-arms. It has the characteristics of both configurations: the high stiffness and accuracy of a parallel robot, and a large workspace and compact structure of a serial robot. Two serial-parallel robotic manipulators (a linkage robot and an articulated arm platform robot) were studied in this research on their direct and inverse kinematics, velocity, dynamics, and collision detection. The direct and inverse kinematics problems were solved using the wrist position of each arm. The inverse velocity problem was solved by the force analysis and the principle of virtual work. Based on the velocity analysis, the singularity problem was researched, and the redundant actuation was analyzed. The dynamic models were established using the Lagrange formulation. An efficient algorithm was introduced to detect link collision. This algorithm can be extended to multiple cooperating robots as well. MATLAB was used to simulate robot motion and to verify various control algorithms. To demonstrate the mobility and capability of a linkage robot, a prototype was built from off-the-shelf components whenever possible. Rhino robot's controller along with its motors is used to control this linkage robot.